This proposal is to establish an AIDS research Clinical Trials Unit (CTU) at the Botswana-Harvard School of Public Health AIDS Initiative Partnership (BHP) in Botswana. The CTU would conduct a fully integrated program for conducting AIDS clinical trials in three programmatic areas: vaccines, therapy, and prevention research. These areas of emphasis would coincide with trials conducted by the HIV Vaccine Trials Network (HVTN), the Adult AIDS Clinical Trials Group (AACTG), and the International Maternal Pediatric Adolescent AIDS Clinical Trials Group (IMPAACT). Trials are already conducted at BHP under the auspices of HVTN and AACTG. The Botswana CTU would include three Clinical Research Sites (CRSs). These would be: (1) the Gaborone-based HIV Vaccine Trial Unit (HVTU) CRS; (2) the Gaborone-based Prevention and Treatment Trial (PTT) CRS, which would do both prevention (IMPAACT) and treatment (AACTG) trials; and (3) the Molepolole-based Prevention and Treatment Trial (PTT) CRS which would also do both prevention (IMPAACT) and treatment (AACTG) trials. This organizational structure is designated as such because vaccine trials would be done only in Gaborone, and the HVTU CRS facility is separate from the PTT CRS facility in Gaborone. The combined resources of the BHP have major expertise in clinical trial research, extensive facilities, and a large and diversified population of potential volunteers for the conduct of Phase I, Phase II, and Phase III trials. We plan to enroll at least 20 subjects in each of the three sites for each respective area of emphasis during the first six months of the award, and have already enrolled much larger numbers on an annual basis in all three areas. Procedures to assure ethical review, clinical oversight, informed consent, government and institutional approvals, and community relations are described. The proposed PI for the CTU, Dr. M. Essex, and the proposed heads for the three CRSs, Drs. T. Villafana, I. Thior, and W. Wester would provide both intellectual and administrative leadership. ADMINISTRATIVE COMPONENT: